1. Field of the Invention
The present invention relates to an improvement to a swingarm support structure.
2. Description of Related Art
A swingarm support section is known from Japanese Patent publication No. Hei. 7-5113, entitled xe2x80x9cRear Arm Mounting Structure For Motorcycle.xe2x80x9d In this technology, as shown in FIG. 1 and FIG, 2 of that publication, plate-like brackets 3, 3 are provided on the left and right of a vehicle body. A support pipe 10 of a rear arm 6 is supported on the plate-like brackets 3, 3 via a pivot shaft 8. The rear arm 6 is swingably attached to the plate-like brackets 3, 3 by screwing a nut 14 onto the pivot shaft 8. Furthermore, cover plates 4, 4 for covering a boss head 8a of the pivot shaft 8 and a tip end of the pivot shaft 8 are attached to the left and right plate-like brackets 3, 3.
However, with the above described pivot shaft 8, the length by which the tip end of the pivot shaft 8 projects from the plate-like brackets 3, 3 varies depending on the torque with which the nut 14 is screwed on. Accordingly, in order to stop a rider""s legs etc. from getting caught on the tip end of the pivot shaft 8, it is necessary for there to be a margin in the depth of the cover plate 4. Furthermore, it is necessary to make the attachment sections for the pivot shift 8 wide in the width direction of the vehicle.
Also, when the pivot shaft 8 is passed through the plate-like brackets 3, 3 and the support pipe 10, there is a concern that the threads of the pivot shaft 8 will be damaged, making it impossible to screw the nut 14 onto the pivot shaft 8.
An object of the present invention is therefore to provide a swing arm support structure having a pivot shaft which does not jut out too far in the width direction of the vehicle. Furthermore, it is an object of the present invention to ensure that the threads of the pivot shaft are not damaged during assembly of the swing arm support structure.
In order to achieve the above-described object, a swingarm support structure according to a first aspect of the present invention is provided in a motorcycle having a seat between a front wheel and a rear wheel, left and right pivot support sections provided on both sides of a vehicle frame below the seat, and a swingarm for supporting the rear wheel swingably supported at the pivot section via a pivot shaft. The swingarm support structure includes a tip end of the pivot shaft hollowed out, a threaded section formed inside the pivot shaft, and a bolt screwed into the threaded section to attach the pivot shaft to the left and right pivot support sections.
As in the related art, a threaded section is formed on a tip end of a pivot shaft. Accordingly, when the left and right pivot support sections are fastened by screwing a nut onto the threaded section, the length to which the tip end of the pivot shaft protrudes varies depending on the torque with which the nut is screwed on as described in detail in FIG. 5 of the present invention. In the first aspect of the present invention, the tip end of the pivot shaft is hollowed out, and a threaded section is formed inside the pivot shaft. Accordingly, by screwing a bolt into the threaded section, the pivot shaft is attached to the left and right pivot support sections.
In view of this construction, the only parts of the pivot shaft and bolt which protrude from the left and right pivot support sections are the heads of the bolts. Therefore, the length to which the pivot shaft and bolts project from the left and right support sections becomes constant. As a result, the only thing protruding from the left pivot support section located on the bolt side, or the right pivot support section, is the bolt head. Accordingly, compared to the related art, the length to which the pivot shaft projects is small.
The tip end of the pivot shaft is hollowed out and threads are formed inside the pivot shaft. Furthermore, when the pivot shaft is inserted into the left and right support sections, the section into which the bolt is to be screwed is not damaged.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.